Three instrument design projects await completion: 1. A vitrectomy instrument system which permits interchangeability of various size instruments; 2. a modification of operating microscope to allow photography of intraocular procedures; and 3. the design of a high-speed photo slit lamp. Electron microscopic studies of vitrectomy biopsy specimens; a systematic study of possible blood toxicity to the retina after intravitreal hemorrhages; and the fluorescein angiographic evaluation of possible preoperative rubeosis iridis and its relation to the postoperative development of rubeosis iridis will be performed.